1. Field of the Invention
The present invention generally relates to a robot used in a security system, in particular, to a method for coordinating cooperative robots so as to expand a detected range of abnormal events and effectively eliminate abnormal situations in an environment.
2. Description of Related Art
With the advancement of technology and improvement in the quality of our life, the safety of our living environment, such as houses, office buildings, laboratories, factories, financial institutions, and other public places, has become one of main concerned issues. Accordingly, in recent years, various industries have been focusing on developing different security systems, and security service provision has become a fast-developing field. However, an existing commercialized security system has not sufficient mobility and intelligence for detecting different situations, so that a mistaken triggered rate/false alarm rate thereof is very high, which not only causes users to be confused but reduces the reliability of the security system as well. Moreover, security patrol is the most disfavored job for many security staffs, and owing to uncontrollable (physical and mental) factors of human, security routines cannot be fully carried out even imposed with complete regulations. Due to the rapid development of robots in recent years, replacing security staffs with mobile robots (referred as robots thereinafter) to carry out security patrol is made possible.
A single patrol robot is disclosed in Japan Pub. No. 2003051082. The patrol robot includes a control system and a plurality of sensors, such as video, audio, heat, temperature, and gas sensors for monitoring the surrounding environment. When the sensor detects the occurrence of an abnormal event, the sensor sends a message to the robot so that the robot goes to where the abnormal event takes place to collect information. The situation is then evaluated by the control system of the robot according to the collected information and is then processed according to the evaluated result. However, since there is only one robot for monitoring the environment, when the area to be monitored is too large and the communication of the robot is obstructed, the robot may not be able to collect the information of the abnormal event in a short time. Besides, if any malfunction occurs in the robot itself, the entire security system will be invalidated. Moreover, in most cases, the abnormal events, such as a moving intruder, fire, or gas, may spread to many different places; thus, the single robot cannot go to all these places to collect information at one time when more than one sensor detect the abnormal events.
A task takeover mechanism in a cooperative robot system is disclosed in U.S. Pub. No. US20050113974, wherein both a pet robot and a security robot are disposed in a particular environment, and when an event takes place in this particular environment, for example, a house owner comes back, the task is handed over from the security robot to the pet robot so that the pet robot can perform related housework; contrarily, if the house owner leaves the house, the pet robot hands over the task to the security robot so that the security robot can carry out security-related works. In addition to being triggered by occurrences of events, the task handover may also be triggered by the location information of the robots. Taking robots disposed at different floors as an example, when a robot at a particular floor leads a guest to a staircase, the robot detects a location mark of the staircase such that it communicates with a robot at another floor and hands over the reception task to the other robot. However, in the task handover mechanism described above, the task can only be handed over from one particular robot to another particular robot, while the task is still executed by only one robot. In other words, in foregoing two inventions, since elimination of an abnormal event (such as fire) is carried out by only a single robot, the abnormal event cannot be eliminated effectively.
Accordingly, there exists a need for providing a method for coordinating cooperative robots (or referred as multiple robots) to carry out the same task effectively.